Browse Prior Art Database

FLIP CHIP CARRIER WITH ADJUSTABLE GROUND LEAD INDUCTANCE

IP.com Disclosure Number: IPCOM000007618D
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2002-Apr-10
Document File: 3 page(s) / 102K

Publishing Venue

Motorola

Related People

James A. Andrews: AUTHOR [+2]

Abstract

This is a description of how the series intercon- nection of plated through holes in a substrate can be used to provide RF stability for a transistor when it is packaged in a flip chip configuration. RF power transistor stability for common source and common emitter configurations is affected by the inductance ofthe respective source and emitter interconnections. In a wire bonded package the optimum inductance is tuned by means of the number, length and diam- eter of the wire bonds used. In a flip chip package, the low inductance of bump interconnections can cause the same transistor to become unstable com- pared to when it is wire bonded.

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M-ROLA Technical Developments

8

FLIP CHIP CARRIER WITH ADJUSTABLE GROUND LEAD INDUCTANCE

by James A. Andrews and John Stafford

  This is a description of how the series intercon- nection of plated through holes in a substrate can be used to provide RF stability for a transistor when it is packaged in a flip chip configuration. RF power transistor stability for common source and common emitter configurations is affected by the inductance ofthe respective source and emitter interconnections. In a wire bonded package the optimum inductance is tuned by means of the number, length and diam- eter of the wire bonds used. In a flip chip package, the low inductance of bump interconnections can cause the same transistor to become unstable com- pared to when it is wire bonded.

  The A&O, chip carrier, represented in Figure 1 makes use of an embedded Cu slug to improve heat dissipation. As represented, the high conductivity heat transfer path for the source (emitter) contact is the same as that for the current path, giving the structure a low source (emitter) contact inductance in a flip chip application.

  The AlN chip carrier, shown in Figure 2, can make use of plated through holes to provide the needed inductance in a: flip chip application. AlN has a thermal conductivity as high as 1.7 W/cm "C and does not require an embedded Cu slug to be used with power devices. However, the cost of the AlN structure is about a factor oftwo or three higher than the Al,O, structure and the maximum...